This invention relates to an electromagnetic pump for pumping electrically conductive liquids, for example, liquid metals, and, in particular, to a pump which uses forces created by interaction of a DC current and a permanent magnetic field to cause the flow of a liquid metal.
Much of advanced technology relies upon electronics and other devices which are subject to high heat loads and require highly efficient cooling. Included in this technology are, for example, x-ray equipment and high-speed computer chips. It is desirable that a cooling system used in such a device be of simple construction, small size and mass, and adaptable to varied environments.
It is well known in the prior art that liquid metals are useful in cooling systems as heat transfer fluids. Liquid gallium is particularly useful because of its high thermal conductivity and high volume specific heat. (See further, U.S. Pat. No. 4,953,191, issued to Smither et al, Aug. 28, 1990, U.S. Pat. No. 5,004,319 issued to Smither, Apr. 2, 1991)
Most prior art electromagnetic pumps produce a force to move a conductive liquid by varying a magnetic field in time (pulsating the field) or in time and space (rotating the field). Generally use of varying magnetic fields and pulsating AC currents requires high voltages to overcome electrical resistance and to produce work.
In addition, overcoming electrical resistances and frictional forces sometimes produces significant amounts of heat. If an electromagnetic pump is used in a cooling system, an additional heat exchanger may be required to remove heat added by operation of the pump.
In addition, most prior art cooling systems cannot effectively remove high levels of heat generated from new high power semiconductor devices or high power X-ray/photon sources.
It is therefore an object of this invention to provide a permanent magnet based pump which is compact and suitable for use in cooling equipment such as for X-ray sources and for computer chips.
It is another object of this invention to provide a pump which is capable of moving conductive fluids at high pressures (such as, 100-900 psi) add/or large fluid volume flow rates with low power requirements.
It is another important object of this invention to provide a pump for which heat generated by pumping action is significantly less than the work of heat transfer to be accomplished and does not require additional cooling.
It is a further object of this invention to present a pump with reversible flow which can be used in a variety of environments including a vacuum.
It is yet another object of the invention to provide a liquid metal heat exchanger unit having greatly improved heat transfer capabilities compared to water based heat exchangers.
It is still a further object of the invention to provide a liquid metal heat exchanger wherein the liquid metal is pumped at high pressure and flow rates through a highly efficient heat extraction network of capillary tubing.
It is yet an additional object of the invention to provide a heat exchanger unit using a liquid metal as the heat extraction media wherein the liquid metal has a very low vapor Pressure and high surface tension enabling safe operation of the heat exchanger.
Additional objects, advantages and novel features of the invention will become apparent to those skilled in the art upon examination of the following and by practice of the invention.